I have a 30 that works great but I find the plastic manual focus ring "hitches" as you turn it...if you relax it then will go smooth again...almost like it needs a tiny bit of silicone lube. Anyone else have that?

Manual focusing is impossible with mine, even using the lightest touch. It always 'jumps' over the sharp point. Fortunately I use mine remotely with AF which is good. This has been reported before and I think one forum member dismantled his and relubricated it with some success.